To dilate internal organs such as a bile duct which are being narrowed or are narrowed by a tumor formed by growth of cancer cells in the villus or its surroundings of the internal organs, medical stents are used.
Various conventional medical stents having various structures are known. As shown in FIG. 1, such a stent is manufactured by weaving a wire 1 formed of a superelastic shape memory alloy or stainless steel so as to be crossed at different positions and by forming a hollow cylindrical body 3 having a plurality of rhombic spaces (cells) 2 and a predetermined length.
To prevent cells growing at a spot where a procedure is to be performed, i.e. cancer cells, from penetrating into the stent, the interior and exterior of the cylindrical body 3 are coated with polytetrafluoroethylene (PTFE) or silicone that is not harmful to a human body.
This stent is manufactured as shown in FIG. 2 by bending and crossing the wire 1 formed of a superelastic shape memory alloy or stainless steel in directions perpendicular to circumferential and lengthwise directions using a basic jig 10 in which a plurality of projecting pins 11 are uniformly assembled in the circumferential and lengthwise directions so as to have a preset diameter Ø and length L, and by forming the rhombic cells 2 so as to be expanded/contracted at intersections in diametrical and lengthwise directions. The stent has an elastic force in the diametrical and lengthwise directions so as to be restored in its original state of a cylindrical shape formed by the basic jig 10 as long as the stent is not forcibly pressed by an external force.
The stent manufactured using this basic jig 10 is disclosed in Korean Unexamined Patent Application Publication Nos. 10-2001-18024 and 10-2001-18026, both of which are the prior applications of the applicant of the present invention.